For what is being hailed as one of Marc Jacobs's best collections ever, the models walked to "Somewhere Over the Rainbow" on a set meant to resemble the inside of a giant cardboard box. Even their clothes were neutral tones. "Marc said the only hint of color he wanted on the runway was in the makeup," François Nars told us.

"They're sexy, cool girls—the kind of girls you see in the East Village, or a café in Paris, or around London," said Nars. "We were thinking about Kate Moss when she's gone out the night before and still has some of her makeup on the next morning, but it's slightly worn off."

That meant all the makeup was applied with a finger—"so it would look a little destroyed," Nars said. He even used old tubes of mascara on the lashes, to assure that they would clump.

We asked him Nars how he collaborates with Marc, and he let us in on what sounded like the most chilled-out scene one could imagine: "We hung out for two days before the show. We just looked at the clothes and listened to music and talked about ideas. The process is very natural."

On the lips, Nars used a discontinued shade that Marc had brought to the hair and makeup test—Nars Barbarella, a pale orange-coral. And on the cheeks: "There's practically no blush, to give that pale, underground type of feel," Nars said as he dotted on just a hint of his Enchanted Cream Blush.

Guido told us that Marc had brought him a still from an old French film as inspiration. "For this collection, it's more about a feeling than a hairstyle," he said. "The girl is sophisticated, but in an easygoing way."

Key to the look: "A great cut, then you can let your hair do its own thing," Guido told us. He trimmed every model's hair to a couple of inches below her collarbone—"the perfect length"—then dampened the hair and applied Redken Fabricate 03 Texturizer and let it all air dry. That was it.

Marc asked his longtime nail pro, Elisa Ferri, to custom blend five different CND polish colors for the show—with the finished products spanning the neutral spectrum from beige to gray. The designer appropriately referred to one color, a mix of both shades, as "Greige."